Reflections and Rotations
Any rotation can be expressed as the composition of two reflections.
In the sketch below, triangle A'B'C' is the result of rotating triangle ABC around point O by angle . Triangle A''B''C'' is the result of reflecting triangle ABC over m followed by n.
Play with the sketch, and decide how to compose and to produce the desired rotation by dragging lines m and n until triangle A''B''C'' coincides with triangle A'B'C'.
Is the composition unique?